Compound bows

ABSTRACT

Improved compound bows which are smaller, more compact, lighter, and more easily handled and serviced than compound bows of conventional construction but are nevertheless capable of propelling an arrow at an equal or higher velocity and with comparable or greater accuracy than a conventional bow. The improved bows are quieter than those of conventional construction and less apt to snag on brush or other obstacles. They have a rigid riser with ends to which string cams are rotatably mounted and cam-associated power units mounted to and towards the ends of the riser. Each power unit has a component which is elastically deformed to store potential energy as the bow is drawn and a power cable connecting the power storing component to the associated string cam. A bow string extends between and is connected at its opposite ends to the string cams. As the bow is drawn, the string cams are rotated in counter directions, pulling on the power unit cables and thereby elastically deforming and storing potential energy in the power unit components. When the bow string is subsequently released, the elastically deformable power unit components restore to rest configurations, this converting the stored potential energy to arrow propelling kinetic energy. A timing cable arrangement insures that the cams are synchronized to rotate in unison, avoiding the unwanted nock travel that might otherwise occur; and the power units have an adjustment feature which allows the force required to fully draw the bow to be changed.

TECHNICAL FIELD OF THE INVENTION

The present invention relates to novel, improved, compound archery bows.

BACKGROUND OF THE INVENTION

The compound bow is a relatively recent development. It has been reported that the first patent on a compound bow is U.S. Pat. No. 3,486,495 issued 30 Dec. 1969.

Modern compound bows are instruments of considerable sophistication and not insignificant complexity.

A bow of this type has a rigid riser with a grip for the archer and flexible limbs extending in opposite directions from the two, opposite ends of the riser. A rotatable cam and a wheel (single cam bow) or two rotatable cams (double cam bow) are mounted to and move with the extreme ends of the flexible bow limbs as the bow is drawn and as the bow string is subsequently released.

A bow string is connected between the cams, which rotate in opposite directions when the bow is drawn. As the bow is drawn, the bow string moves away from the limb/riser assembly of the bow. This displacement is the greatest at the location where the arrow is nocked to the bow string.

Modern compound bows typically have cam surfaces with a let-off segment contacted by the bow string for that part of the draw ending with the bow being fully drawn. The let-off reduces the force required to draw the bow over that part of the draw where the let-off is in play. Also, the force required to hold the bow at full draw is reduced, which is of obvious benefit to the archer.

When a conventional, double cam, compound bow is drawn, the two cams of the bow tend to rotate at different rates. As a result, one cam can reach the beginning of its let-off before the other cam does. If this happens, the cam that is lagging behind will overpower the cam which reaches let-off first. This causes the leading cam to rotate backwards, i.e., in the same direction as the lagging cam. As a result, the nock position of the arrow becomes unstable and moves up (or down) from the centered position. A conventional compound bow of the type under consideration is not self-centering, and this movement of the nock position away from the centered position continues until full draw is reached. This displacement of the nock position makes an accurate shot unlikely, if not impossible.

A relatively complicated and expensive buss system is conventionally employed to ensure that the two cams of a double cam, compound bow rotate in unison and that the two cams accordingly reach let-off simultaneously, even though the buss system adds complexity and cost to a bow. A typical buss system has buss cables which extend between the string cams of the bow and are connected to the string cams and the limbs of the bow; a cable guide; and a riser-mounted support for the cable guide.

Aside from its complexity and cost, the buss system of a conventional bow has the disadvantage that the buss system cables are moved sideways to clear the arrow path as the bow is drawn. This puts sideways pressure on the bow limbs, which causes them to drift sideways. When the arrow is released, the bow limbs snap back into alignment. This sudden movement also contributes to the inaccuracy of a shot made from a conventional compound bow.

The bow is drawn by pulling on a bow string which is anchored to the cams (or cam and wheel) of the bow. When the bow string is released, the flexible limbs of the bow restore toward their rest configurations; and the potential energy stored in the limbs is converted to kinetic energy, rapidly displacing the bow string to its rest configuration and launching an arrow nocked to the bow string.

A conventional compound bow has a large mass in motion when an arrow is released, due in large part to the moving mass of the bow limbs and cams as the limbs restore from the stressed configurations they have at full draw to their rest configurations. When the limbs and other moving bow parts reach their rest configurations, they slam to a stop; and shock and vibration are set up in the bow and transferred by way of the bow riser to the archer. The shock and vibration can cause the archer to flinch because of the sting felt when the arrow is fired. Flinching leads to a wild shot.

Another disadvantage of many compound bows is that they are noisy, in large part due to the vibration-caused rattling and other movements of bow components as they move to and reach their rest positions. Particularly in the case of a close shot, a game animal can clearly hear and locate the bow noise and react fast enough to move before the arrow reaches the animal. This may result in a wounded animal or a missed shot.

Also, the flexible limbs of a conventional compound bow are susceptible to breakage, especially if a bow is dry fired; i.e., discharged without an arrow. The repair and other problems a broken bow limb can cause a hunter in the field are obvious, and a breaking bow limb can fly into and seriously injure the archer.

SUMMARY OF THE INVENTION

Novel, improved bows which are free of the disadvantages identified above and which have other significant benefits have now been invented and are disclosed herein.

The novel bows of the present invention have an elongated, rigid riser. This riser may be of a skeleton construction, desirably reducing the weight of this component and making the bow aesthetically pleasing.

Like a conventional compound bow, those disclosed herein have string cams to which the opposite ends of a bow string extending in the direction of the riser's axis of elongation are attached. However, these cams are rotatably mounted to opposite ends of the rigid riser rather than to the ends of flexible limbs as they are in a conventional compound bow. Consequently, the cams rotate as the bow is drawn and upon bow string release, but the cams do not otherwise move during the bow drawing/bow string release cycle.

The force for propelling an arrow is generated in bows embodying the principles of the present invention by string cam-associated power units. These power units are also mounted at the ends of the rigid riser and, like the string cams, they do not, as a whole, move during the bow drawing/bow string release cycle.

Each of the cam string-associated power units includes an elastically deformable power-generating component which is anchored at one end and free to move at the second, opposite, component end. The free end of each power-generating component is fixed to a power cam which rotates with the associated string cam by a power cable or other force/motion transmitting mechanism. Therefore, when the bow is drawn by pulling on the bow string at the midpoint of that component, the string cams are rotated (in opposite directions), concomitantly rotating the power cams and pulling on the power cables, thereby elastically deforming the power-generating components and storing potential energy in those components. When the bow string is subsequently released, the force-generating components restore to their rest positions, converting the stored potential energy to kinetic energy for propelling an arrow from the bow.

As in the case of a conventional bow, it is important that the string cams of a bow embodying the principles of the present invention rotate in unison to eliminate (or at least drastically reduce) nock travel and the degradation in accuracy attributable to that phenomenon. The buss system employed in a conventional bow and the problems associated with such a system are eliminated by using a simple timing cable which is fixed at its opposite ends to riser-mounted timing wheels. These wheels rotate with the string cams as the bow is drawn and after the bow string is subsequently released.

Another of the important advantages of the bows disclosed herein is that they have low residual energy; i.e., there is very little energy left in the bow after the arrow leaves the bow. In contrast, a conventional compound bow has high residual energy because of the substantial mass of the bow components moving to their rest positions when an arrow is released and the large displacements of those components. These components include the long and relatively heavy limbs of a conventional bow; the weighty, limb-mounted string cams, which move forwardly and outwardly through considerable distances at the ends of the bow limbs; and the components of the buss system including its cables and the slide used to keep the buss cables out of the path of the arrow as it is propelled from the bow.

The residual energy in a typical compound bow is so high that the bow actually shakes as the moving bow components reach their rest positions and come to a stop. All of this residual energy is converted to noise and other vibrations and ultimately to heat. One important adverse effect of high residual energy is the degradation in accuracy attributable to the bow shaking. Another is that a conventional bow with its high residual energy is inefficient because a significant part of the energy generated when the bow string is released remains in the bow instead of being transferred to the arrow propelled from the bow.

In contrast, the bows disclosed herein have only low residual energy because: (a) the string cams rotate but do not otherwise move relative to the riser of the bow at arrow launch; (b) the deformable, force-producing components of the power units are small and light and move through only small distances (typically not more than 1.5 inches) to their rest positions; and (c) there are no buss system components contributing to the residual energy. Thus, essentially the only residual energy is that generated by rotation of the string cams, the movement of the bow string and a timing cable to their rest configurations, and the small amounts of energy generated by the restoration to their rest configurations of the force-producing power unit components. The remaining energy is transmitted to the arrow as it leaves the bow. This results in a higher initial arrow velocity with a corresponding increase in accuracy and other performance factors.

Thus, a bow embodying the principles of the present invention is very efficient. Because the residual energy is low, there is little noise or vibration; and the bow is smooth, quiet, and efficient.

Also, as the string cams are fixed relative to the riser in a bow as disclosed herein instead at the ends of relatively long and flexible limbs, the cams do not flail around when an arrow is released as they do in a conventional, compound bow. This further contributes to the accuracy of the bow because the bow shoots straighter and the operation of the bow remains consistent from shot to shot.

A further gain in accuracy is realized by elimination of the buss system employed in a conventional compound bow. The cables of a conventional buss system pull the string cams of a bow off center, torquing or twisting the limbs to which the cams are mounted. This both reduces the accuracy of a specific shot and reduces the repeatability of a conventional bow from shot to shot.

The elimination of the buss system in the bows disclosed herein essentially, if not completely, eliminates the side torque effect unavoidable in many conventional compound bows. Furthermore, any small torquing effect that might be present is negated because the cams are mounted to a bow component —the bow riser—which is rigid and does not twist like the cam-supporting limbs of a conventional compound bow do.

Yet another important advantage of the present invention is realized by elimination of the buss system employed in a conventional compound bow. This system has buss cables fixed to the extreme ends of the bow; specifically, at the outermost ends of the flexible bow limbs and to buss cams which rotate with the string cams. When the bow is drawn, the buss cables place the bow's riser, especially its central, hand grip segment, under a very large load, creating a correspondingly large bending moment in the riser. The elimination of a buss cable system in the bows disclosed herein eliminates such stress, allowing the riser to be made significantly lighter than a riser of conventional construction because the only load placed on the riser is that of the bow string. At the same time, the riser is less susceptible to distortion, even if lighter; and the precision with which an arrow can be shot is correspondingly increased.

The force-generating components of the power units employed herein may be attached with a simple adjusting screw mechanism which both allows the bow to be readily disassembled for string and component replacement, even in the field, and makes it equally simple to adjust the force required to draw the bow from essentially zero up to the typical maximum of 70 pounds. No bow press is needed, and the force-generating components are so small that spares can be slipped into an archer's pocket. These are significant practical advantages, especially to a bow hunter.

Because they are so small and are elastically deformed to only a very limited extent, even at full draw of the bow in which they are incorporated, the force-generating components disclosed herein are highly resistant to breakage, even if the bow is dry fired or the bow string is cut in the course of loading a broadhead or other sharp arrow; and these force-generating components can be easily shrouded so that, in the unlikely event one breaks, parts which come loose will be contained instead of flying around and possibly hitting and injuring the archer. This eliminates a serious drawback of conventional compound bows which, when a limb breaks, may leave parts of the limb flying like a missile or flailing around on the bow string. The bows of the present invention are therefore safer to shoot than conventional compound bows are, and product liability is significantly less of a problem for manufacturers and sellers. Also, because they are shrouded, the power-generating components are unlikely to catch or snag on brush or other obstacles, a recurring problem experienced by hunters using conventional compound bows.

Another important advantage of the novel bows disclosed herein is that an arrow release need not be used, even though the bow may be very short. In a conventional compound bow of short length, the limbs bend toward the midpoint of the bow as the bow is drawn; the string cams move closer together; and the angle between the two bow string segments on opposite sides of the nocked arrow becomes very steep, making it impossible to securely grasp the bow string with one's fingers. Also, because of this severe or sharp angle, short bows of conventional construction are twitchy and hard to shoot accurately.

Because they are riser-mounted, this distance between the strings cams of the bows disclosed herein does not decrease as the bow is drawn; and the angle between bow string segments is less severe, even at full draw, allowing the string to be securely grasped without an arrow release. This feature is preferably enhanced by employing string cams eccentrically mounted off center relative to the bow riser such that the distance between the locations at which the bow string is attached to the cams significantly increases between zero and full draw. In addition, because of the eccentric mounting of the string cams, the ends of the bow string lie well above and behind the riser of the bow, creating a much more gradual angle between bow string segments than is possible in a short compound bow of conventional construction. Thus, while there may typically be only a 32 inch span between the axles of the string cams, a bow embodying the present invention will shoot like a long, 40 inch conventional compound bow because of the increasing distance between cam/string points of attachment as the bow is drawn. This makes the bow very forgiving and easy to shoot accurately.

Instead of a buss system for synchronizing string cam rotation, the bows disclosed herein employ a FIG. 8 timing cable stretched between and anchored to timing cams which rotate with the string cams of the bows. Because they are thus fixed to the riser of the bow instead of to the limbs, which move rearwardly over a considerable distance as a conventional compound bow is drawn, the imposition of significant bending moments on the bow riser and the drawbacks appurtenant to such moments is avoided.

Other important objects, advantages, and features of the invention will be apparent to the reader from the foregoing and the appended claims and as the ensuing detailed description and discussion of the invention proceeds in conjunction with the accompanying drawings.

PRIOR ART

U.S. Pat. No. 2,116,650 to Zima discloses a bow which has a “primary bow-leaf of wood . . .” Arrow propelling energy is generated by “a helical tension spring located at the middle of the bow-leaf.”

U.S. Pat. No. 2,307,021 to Cordrey et al. discloses a bow with a frame 1. Elastic tubes 15 are mounted on the frame and employed: “for propelling . . . [an] arrow” from the bow.

U.S. Pat. No. 3,518,980 to Hamm discloses a bow with “an elongated bow frame member 12.” Member 12 houses tension springs which are used to generate the energy for propelling an arrow from the bow.

U.S. Pat. No. 3,595,213 to Storer discloses a bow with an elastic band 46 for generating arrow propelling energy.

U.S. Pat. No. 3,744,473 to Nishioka discloses a bow with “resilient tensioning springs” 26 and 27.

U.S. Pat. No. 4,903,677 to Colley et al. discloses a bow with a “flat wound power spring . . . [91] mounted on a frame . . .”

U.S. Pat. No. 4,989,577 discloses a bow with a mouse trap type spring for generating arrow propelling force.

U.S. Pat. No. 5,054,463 to Colley et al. discloses a bow with “flat wound power springs” 80 and 81 (FIG. 10).

U.S. Pat. No. 5,638,804 to Remick et al. discloses a bow with “energy storage limbs” 86 and 87.

U.S. Pat. No. 6,698,413 discloses a bow with a “variably compressible power coil spring.”

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an isometric view of a compound bow constructed in accord with, and embodying, the principles of the present invention;

FIG. 2 is an isometric view of one end of the FIG. 1 bow; this figure is drawn to an enlarged scale to better show operating components of the bow;

FIG. 3 is a side view of the FIG. 1 bow; this view is partially sectioned to show power units with elastically deformable, potential energy storing components at the two, opposite ends of the bow; deformation of the power units followed by restoration of those units to their rest configurations provides kinetic energy for propelling arrows from the bow;

FIG. 3A is a fragment of FIG. 3 drawn to an enlarged scale to better show a mechanism employed in the FIG. 3 power unit to hold an elastically deformable component of the power unit in place and to change the pull required to draw the bow;

FIG. 4 is a fragment of FIG. 3 drawn to an enlarged scale to better illustrate one of the two, like power units employed in the FIG. 1 bow and the relationship of the power units to other bow components; bow components are shown in their “rest” positions and configurations;

FIG. 5 is a view similar to FIG. 4 but with: (a) the bow string drawn to rotate a cam to which the illustrated end of the bow string is attached, (b) thereby shortening the effective length of a motion/force transmission power cable connected between the cam and the elastically deformable power unit component to (c) elastically deform and thereby store that potential energy which is converted to arrow propelling kinetic energy when the bow string is subsequently released;

FIG. 6 is a view similar to FIG. 4 but is taken from the opposite side of the FIG. 1 bow to show a timing cable mechanism provided to insure that the two string cams at the opposite ends of the bow rotate in unison;

FIG. 7 is a view similar to FIG. 6; this view shows how elements of the timing cable mechanism move as the bow is drawn to synchronize the rotation of the two riser-mounted string cams;

FIG. 8 is a side view of a timing system wheel; one such wheel is mounted at each end of the riser of the FIG. 1 bow;

FIG. 9 is a view of the FIG. 1 bow which is oriented at a right angle to the FIG. 1 view;

FIG. 10 is a side view of a second compound bow constructed in accord with, and embodying, the principles of the present invention;

FIG. 11 is a fragmentary side view of the FIG. 10 bow with the bow components in their “rest” positions and configurations; this view is drawn to an enlarged scale and partially sectioned to show one of two power units located at opposite ends of the bow; the power units provide energy for propelling arrows from the bow;

FIG. 11A is a fragment of FIG. 11 drawn to an enlarged scale to better show a mechanism employed in the FIG. 11 power unit to keep an elastically deformable power unit component in place and to adjust the pull required to draw the FIG. 10 bow;

FIG. 12 is a view similar to FIG. 11 but with: (a) the bow string drawn to rotate a riser-mounted cam to which the upper end of the bow string is attached, (b) thereby shortening the effective length of a cable connected between the string cam and the power unit to (c) elastically deform and store potential energy in the power unit;

FIG. 13 is a fragmentary, partially sectioned side view of a bow constituting a third embodiment of the invention; this bow has riser-mounted timing system idlers and is shown with the bow components in their “rest” relationships and configurations; and

FIG. 14 is a view like FIG. 13 but showing the bow components in the relationships and configurations they assume when the bow is drawn.

DETAILED DESCRIPTION OF THE INVENTION

Referring now to the drawings, FIGS. 1 and 2 depicts a compound archery bow 20 constructed in accord with and embodying the principles of the present invention. The major components of bow 20 include an elongated, rigid riser 22; string cams 24 and 26 at the upper and lower ends 28 and 30 of riser 22; a timing system 32 (see especially FIGS. 6-8), including a timing cable 34 for synchronizing the counter rotation of string cams 24 and 26 suggested by arrows 36/38 and 40/42 in FIG. 1; and riser-mounted power units 44 and 46 (see especially FIGS. 3-6) which store arrow propelling energy in potential form as bow 20 is drawn. A bow string 48 extends between and is connected at its opposite ends 50 and 52 to the upper and lower string cams 24 and 26. With the components of bow 20 in their rest configurations and positions, bow string 48 lies along a straight line located to the rear of riser center section 54. When bow 20 is fully drawn, bow string 48 is configured as shown in phantom lines in FIG. 1 and in full lines in FIG. 3.

The rigid riser 22 of bow 20 has an elongated configuration defined by the just-mentioned center section 54 and integral, upper and lower arms 56 and 58, which are oriented at equal angles to, and extend rearwardly toward the archer from, the bow string side 60 of riser 22. A hand grip 62 is formed in riser center section 54 at a location between the junctures 64 and 66 of: (a) the riser center section 54 and riser upper arm 56 and (b) center section 54 and lower riser arm 58.

Riser 22 may be skeletonized as is perhaps best shown in FIGS. 1-3. This desirably reduces the weight of bow 20 and gives the bow an esthetically pleasing appearance.

Because riser 22 is a fairly large component, it is preferably fabricated from a material which is lightweight, strong, and rigid. At the present time, conventional carbon composites are the materials of choice. This is not intended to be limiting, however, as a variety of other materials may instead be employed. These include, without limitation, aluminum and titanium alloys, fiber-reinforced polymers, carbon-reinforced polymers, and glass-loaded polymers. Also, a combination of materials such as an aluminum alloy and a carbon composite may be employed with selected elements of the riser being made of the alloy and the rest of the riser from the carbon composite.

Similarly, a variety of manufacturing techniques may be employed to fabricate the riser. In the case of a carbon composite, molding with a bladder that can be expanded to produce a hollow cavity in the may be employed.

The string cams 24 and 26 at the upper and lower ends 28 and 30 of riser 22 are like components. Accordingly, only the upper cam 24 will be described in detail with the understanding that this description also applies to lower cam 26.

Upper cam 24 is mounted to the upper arm 56 of riser 22 between riser limbs 67 and 68 at the free end 69 of riser arm 56 for rotation on an axle 70 about a transverse axis 71. Axis 71 is offset from the center of cam 24, the cam accordingly rotating upwardly and to the rear as bow 20 is drawn (compare FIG. 5 with FIG. 4).

This eccentric mounting of string cams 24 and 26 is an important feature of the present invention. In a representative bow embodying the principles of the present invention, the axle-to-axle span of the bow; i.e., the distance 72 between upper string cam axle 70 and lower string cam axle 74 is only 32 inches; and bow 20 is accordingly, and desirably, very compact. However, because the cams are mounted so far off center, they rotate upwardly and back as described above when bow 20 is drawn to the extent that the bow shoots more like a 40-inch bow when it is fully drawn; and the string angle 75 is much smaller than that of a conventional short (e.g., 32 inch) bow. As a consequence, an arrow release is not needed, the bow can be drawn with the archer's fingers; and the bow is very forgiving and easy to shoot accurately.

It was pointed out above that a timing system 32 is employed to synchronize the rotation of upper and lower cams 24 and 26: (a) as the bow is drawn and the upper and lower cams counter rotate in the arrow 36 and 38 directions, and (b) when bow string 48 is subsequently released to launch or propel a nocked arrow from the bow, the upper and lower string cams 24 and 26 counter rotating in opposite, arrow 40 and 42 directions in this part of the shooting cycle. Referring specifically to FIGS. 6-9, timing system 32 comprises the above-mentioned timing cable 34; a dual track, upper timing wheel 76; and a lower, also dual track timing wheel 78 (FIG. 3). The details of the upper timing wheel 76 and its association with and relation to timing cable 34 are shown in detail in FIGS. 6 and 7; and the ensuing discussion will be directed to the components shown in those figures with the understanding that the discussion is equally applicable to the timing wheel arrangement at the lower end of bow 20.

Focusing then on FIGS. 6 and 7, timing wheel 76 is mounted to upper string cam 24 and rotates with that cam in the arrow 36 direction as bow 20 is drawn and the upper segment 80 of the bow string attached at upper bow string end 50 to string cam 24 moves in the arrow 82 direction to rotate the cam. Timing wheel 76 rotates with string cam 24 in the opposite direction to its rest position when the bow string 48 is subsequently released to shoot a nocked arrow from the bow.

Timing cable 34 is guided through an aperture 83 in riser arm 56 and is fashioned into the illustrated FIG. 8 configuration so that the two runs 84 and 85 of the timing cable will move in the opposite directions indicated by arrows 86 and 87 when bow 20 is drawn, thus providing for the counter rotation of upper and lower string cams 24 and 26 in the opposite, arrow 36 and 38 directions.

Timing cable runs 84 and 85 are pinned or otherwise attached in outer and inner tracks 88-1 and 88-2 of upper timing wheel 76 at the locations indicated by arrows 89 and 90 in FIG. 8 and are similarly affixed to lower timing wheel 78. Consequently, when bow 20 is drawn and the two cable runs 84 and 85 are displaced in the opposite, arrow 86 and 87 directions by the counter rotation of upper and lower timing wheels 24 and 26, the two timing wheels 76 and 78 are constrained to rotation in unison, synchronizing or matching the rotation of the string cams to which the timing wheels are fixedly mounted. It is important, in this regard, that timing cable 34 be inextensible, though flexible, so that the counter rotation of string cams 24 and 26 will be precisely synchronized during the bow drawing and arrow launching parts of the shooting cycle.

Absent restraint, timing cable 34 would lay along the path identified by reference character 100 in FIG. 9 and would consequently interfere with the fitting of an arrow to the bow and with the flight of the arrow when bow string 48 is released. To avoid these problems, timing cable 34 is held to the side and away from the arrow flight path by routing it through features or fixtures 102 and 104 integrated with the center section 54 of bow riser 22 on opposite sides of hand grip 62. As a nocked arrow lays slightly to the right of path 100 with bow 20 oriented as shown in FIG. 9, fixtures 102 and 104 keep timing cable 34 well away from the arrow path.

It was pointed out above that the power or energy for propelling or launching an arrow from bow 20 is generated by small, lightweight, compact components of power units 44 and 46 rather than by the long, heavier, cumbersome flexible bow limbs utilized for this purpose in a conventional compound bow. Upper power unit 44 will now be described in detail with reference especially to FIGS. 3-5 and with the understanding that the discussion is also equally applicable to the like lower power unit 46.

Power unit 44 includes a small, elongated, riser-mounted component 106 which is elastically deformed (see FIG. 5) as bow 20 is drawn, storing potential energy in the component. When bow string 48 is subsequently released, component 106 restores to the rest configuration depicted in FIG. 4; and the stored potential energy is converted to kinetic energy for launching or propelling a nocked arrow from the bow.

Power unit 44 also includes a power cam 108 and an anchor 110, both fixed to and rotatable with, upper string cam 24 and a power cable 112. The power cable 112 is fixed at its opposite ends 114 and 116 to the free end 118 of elastically deformable power unit component 106 and to anchor 110, the power cable 112 wrapping around power cam 108 as bow 20 is drawn. As this occurs (see FIG. 5), upper bow string segment 80 moves in the arrow 124 direction, rotating string cam 24 in the arrow 36 direction because of the connection between the bow string 48 and the string cam 24, The rotation of cam 24 and consequent wrapping of power cable 112 around power cam 108 moves the power cable in the arrow 126 direction, elastically bending deformable component 106 of the power unit as indicated by arrow 128 in FIG. 5 thus, as discussed above, storing in that component potential energy which is converted to arrow propelling kinetic energy when bow string 48 is subsequently released and bow string 48, string cam 24, power cable 112, and elastically deformable power-generating component 106 restore to the rest configurations depicted in FIG. 5.

As is shown in FIGS. 1-5, the power-generating component 106 of power unit 44 is housed in a pocket 130 at the juncture between the upper end 131 of riser center section 54 and the lower, forward end 132 of integral riser arm 56. Thus, the riser 22 surrounds and shrouds power unit component 106 and, in the highly unlikely event that component 106 should break, keeps parts of the component from flying around and possibly injuring the archer. Also, the shrouding of component 106 minimizes the chances of bow 20 hanging up on brush or other obstacles.

As is best shown in FIG. 5, power cable 112 is housed over the major portion of its length in upper riser arm 56. This further reduces the possibility that bow 20 might hang up and also makes it unlikely that power cable 112 might fly around and perhaps injure the archer if it breaks.

At its lower end 136, elastically deformable power unit component 106 is anchored to bow riser 22. Specifically, lower component end 136 is trapped between a riser-integrated lug 138 on one side of the component and complementary, also riser-integrated, lugs 140 and 142 on the opposite side of component 106. Component 106 is kept from slipping out of riser 22 by a screw 144 threaded through an integral riser fitting 146 in which a screw-receiving dowel 147 is installed for increased strength. The inner end (or tip) 148 of screw 144 is trapped in a dimple 150, which is formed in a plate 152 bonded or otherwise attached to power unit component 106 (FIG. 6A).

Also, by threading screw 144 in and out of integral fitting 146, the biasing force exerted by power unit component 106 can be changed, allowing the pull required to draw bow 20 to be varied from near zero to the maximum for which the bow is designed (typically on the order of 70 lbs.).

The elastically deformable, energy-storing components 106 of power units 44 and 46 may be fabricated from a variety of materials with carbon composites currently being preferred because of the low weight and precision-providing rigidity of such materials as well as their ability to accommodate the severe bending of the elastically deformable power unit components 106 as bow 20 is drawn. Other materials that may be employed include, but are not limited to, composites of S-glass fibers and other glassy reinforcements in epoxy, Nylon, and other polymeric matrixes; carbon reinforced polymers; metallic glasses; and alloys of aluminum and titanium.

There is a variable ratio—typically from 3:1 at rest to a very high 10:1 at full draw—between the power cable track 154 of power cam 108 and the string cam track 156. This high cam track ratio maximizes the amount of energy transmitted to the arrow and minimizes the residual energy remaining in the bow when the arrow is shot, both desirable attributes of bows embodying the principles of the present invention. These goals—a maximum transfer of energy to the arrow and low residual energy in the bow—are furthered by preloading the bow, typically to a force on the order of 200 pounds.

Referring still to the drawings, FIGS. 10 and 11 depict a second bow 180 constructed in accord with and embodying the principles of the present invention. Like components of bows 20 and 180 are identified in the drawings by the same reference characters.

Bow 180 differs from the bow 20 discussed above in one respect in the character of its upper and lower, riser-mounted power units (the upper power unit is shown in FIGS. 11 and 12 and identified by reference character 182). Power unit 182 has an elastically deformable, energy-storing component 184 with a curved, integral segment 186 extending from the free end 188 of the component toward the opposite, anchored, component end 190. This configuration keeps the free end or tip 188 of component 184 perpendicular to the power cable 192 of power unit 182 as bow 180 is drawn (compare the tip/power cable relationships shown in FIGS. 11 and 12). Power cable 192 is thereby kept from pulling off of component tip 188 when bow 180 is drawn. That this be done is important as the bow would cease to function if power cable 192 pulled off the tip 188 of power unit component 184; and, in the worst case, the bow would break.

The power unit 182 of bow 180 also differs from the corresponding unit of bow 20 in the particulars of the mechanical arrangement or mechanism employed to mount power unit component 184 to the riser 194 of bow 180. Specifically, a threaded component 196 with a head 198 extends through a washer 200 and the anchored end 190 of power unit component 184 and is threaded into an integral fitting 202 of riser 194 with the tip 204 of component 196 threaded into or through a dowel 206 (FIG. 11A). Dowel 206 is made of a material with the strength needed to keep the threaded component 196 from pulling out of the fitting.

With bow 180 preloaded for the purposes discussed above in conjunction with bow 20, the anchored end 190 of elastically deformable power unit component 184 is biased away from riser fitting 202 as suggested by arrow 208 in FIG. 12. Consequently, by advancing and backing off threaded component 196, the pull required to draw bow 180 can be changed due to the connections between elastically deformable component 184 and bow string 48.

In addition, bow 180 differs from above-discussed bow 20 in its bow riser construction. This riser does not have the skeletonized construction of the riser 22 of bow 20. Instead, apertures collectively identified by reference characters 210 and 212 are formed in the integral upper and lower arms 214 and 216 of the riser to reduce the weight of the bow.

FIGS. 13 and 14 depict yet another compound archery bow 230 constructed in accord with, and embodying, the principles of the present invention. Like components have again been identified by the same reference characters.

Bow 230 is much like the bow 180 depicted in FIGS. 11 and 12 but differs from the latter in that timing system idlers are rotatably mounted near the upper and lower ends of the bow riser 194. The idler mounted to upper riser end 231 is shown in FIGS. 13 and 14 and identified by reference character 232.

Run 85 of timing cable 34 is trained around idler 232. As bow 230 is drawn, string cam 24 rotates in the arrow 234 direction from the position shown in FIG. 13 to the position shown in FIG. 14. Idler 232 increases the angle through which timing cable run 85 is wrapped around upper timing wheel 76 from approximately 200 to about 230 degrees as bow 230 is drawn. This provides the approximately 210 degrees of wrap required to ensure that timing cable 34 will not inhibit the clockwise, arrow 234 rotation of string cam 24 as bow 230 is drawn plus a significant safety margin. Adequate string cable wrap is important because interference with the rotation of string cam 24 would, of course, keep bow 230 from operating properly, if at all.

The principles of the present invention may embodied in forms other than those specifically disclosed herein. Therefore, the present embodiments are to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description; and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced herein. 

1. The combination of a compound bow and a bow string, the bow comprising: a riser; first and second string cams rotatably mounted to opposite ends of the riser for counter rotation in first directions as the bow is drawn and in second, opposite directions when an arrow is shot from the bow; and string cam-associated power units which: (a) are mounted at opposite ends of the riser, and (b) are operable, as the bow is drawn, to store potential energy which is subsequently converted to arrow propelling kinetic energy when the bow string is subsequently released; the bow string extending between and being connected to the string cams.
 2. A combination as defined in claim 1 wherein the riser of the compound bow has: an elongated center section with a hand grip intermediate its ends; and first and second arms; each arm being integrated at one end thereof with an end of the center section; each arm being oriented at an angle relative to a bow string side of the riser and terminating in a free end spaced from a bow string side of the riser; and the string cams being rotatably mounted to the free ends of the riser arms.
 3. A combination as defined in claim 2 in which: each of the string cam-associated power units of the compound bow has an elastically deformable component for storing potential energy as the bow is drawn.
 4. A combination as defined in claim 3 wherein there is a pocket at the juncture of each riser arm and the riser center section housing, each pocket housing an elastically deformable power unit component.
 5. A combination as defined in claim 3 in which each of the power units of the compound bow has a motion/power transmitting component connected between the deformable, energy storing component of the unit and the corresponding string cam.
 6. A combination as defined in claim 1 in which each of the power units of the compound bow comprises: an elastically deformable, energy storing component anchored relative to the riser; and a motion/force transmitting component so operatively connected between the elastically deformable component and the corresponding string cam as to deform and store potential energy in that component as the bow is drawn and the string cam rotates in its first direction.
 7. A combination as defined in claim 1 wherein the motion/force transmitting component of the power unit is attached to and displaces the free end of the elastically deformable component as the corresponding string cam rotates in its first direction.
 8. A combination as defined in claim 6 wherein the elastically deformable component of each power unit of the compound bow is so configured that the free end of that component follows a path which remains generally normal to the motion/force transmitting component of the power unit as the free end of the elastically deformable component is displaced.
 9. A combination as defined in claim 6 in which each power unit of the compound bow has a mechanical adjustment feature for so displacing the anchored end of that unit's elastically deformable component as to change the magnitude of the pull required to effect a full draw of the bow.
 10. A combination as defined in claim 6: in which each of the power units of the compound bow comprises a power cam and an anchor, both rotatable with the associated string cam; and the unit's motion/force transmitting component: (a) is trainable around the power cam as the bow is drawn, and (b) has an end affixed to the anchor.
 11. The combination of a compound bow and a bow string for drawing the bow and for launching an arrow nocked on the bow string when the bow string is subsequently released, the compound bow comprising: a riser; first and second string cams so rotatably fixed relative to opposite ends of the riser that the distance between the axes of rotation of the string cams remains essentially unchanged as the bow is drawn and as an arrow is propelled from the bow when the bow string is subsequently released; and the bow string being enabled to draw the bow and to launch the arrow when the bow string is subsequently released.
 12. A combination as defined in claim 11 wherein: the bow string is so connected between and fixed at opposite ends to the rotatably mounted string cams that displacement of the bow string to draw the bow effects counter rotation of the string cams; and the bow further comprises cam-coupled power unit components which are elastically deformable by rotation of the string cams when the bow is drawn to store potential energy that is convertible to arrow propelling kinetic energy when the bow string is released.
 13. A combination as defined in claim 12 in which the power units of the compound bow are housed in and shrouded by the riser of the bow.
 14. A combination as defined in claim 12 in which the power units of the compound bow each comprise a mechanical arrangement for so adjusting the load on the elastically deformable component of the unit as to change the force required to effect a full draw of the bow.
 15. The combination of a compound bow and a bow string: the compound bow comprising a riser and first and second string cams rotatably mounted to opposite ends of the riser; the bow string extending between the string cams, and opposite ends of the bow string being fixed to the string cams such that the cams are counter rotated in: (a) first directions as the bow string is pulled to draw the bow, and (b) in second, opposite directions when the string is subsequently released to propel an arrow from the bow; and the bow further comprising a timing mechanism for synchronizing the rotations of the string cams, the timing mechanism comprising: first and second timing wheels respectively rotatable with the first and second string cams; and a flexible, generally inextensible component which extends between and is fixed to the first timing wheel and to the second timing wheel.
 16. A combination as defined in claim 15 wherein the flexible timing mechanism component has a figure 8 configuration.
 17. A combination as defined in claim 15 in which the compound bow has at least one feature for holding the flexible timing mechanism component out of the path followed by an arrow as the arrow leaves the bow.
 18. A combination as defined in claim 15 in which: each of the first and second timing mechanism wheels has a surface around which the flexible timing mechanism component can wrap as the bow is drawn; and the timing mechanism further comprise an idler so positioned relative to each of the first and second timing wheels as to change the path of the flexible timing mechanism component in a manner which increases the angle through which that component can wrap around the timing wheel at full draw of the bow and keeps rotation of the timing wheel from interfering with the draw of the bow.
 19. A compound bow which comprises: a riser; first and second string cams rotatably mounted to opposite ends of the riser for counter rotation in first directions as the bow is drawn and in second, opposite directions when an arrow is shot from the bow; string cam-associated power units which are mounted at opposite ends of the riser; and a mechanical timing mechanism for synchronizing the counter rotation of the first and second string cams in their first directions and in their opposite, second directions.
 20. A compound bow as defined in claim 19 wherein each power unit includes an elastically deformable component and a motion/force transmitting mechanism so connecting the elastically deformable component to the associated string cam that: (a) rotation of the string cam in its first direction as the bow is drawn so deforms the elastically deformable component as to store potential energy in that component, and (b) subsequent rotation of the cam in its opposite direction when the bow string is subsequently released and frees the elastically deformable power unit component for restoration to its rest configuration with a concomitant conversion of the potential energy stored in the component to arrow propelling kinetic energy.
 21. A compound bow as defined in claim 19 wherein the riser of the bow is of rigid construction and has: an elongated center section with a hand grip intermediate its ends; and first and second arms, each arm being integrated at one end thereof with an end of the riser section, each arm being oriented at an angle relative to a bow string side of the riser center section and terminating in a free end spaced from the bow string side of the riser; the string cams being rotatably mounted to the free ends of the riser arms.
 22. A compound bow as defined in claim 19 wherein the motion/force transmitting component of the power unit comprises: an anchor mounted to the associated string cam for rotation therewith; a power cable connected between the elastically deformable power unit component and the string cam-mounted anchor; and a power cam so mounted to the string cam that the power cable can wrap around the power cam as the bow is drawn and the string cam consequentially rotates in its first direction.
 23. A compound bow as defined in claim 22 wherein: the elastically deformable power unit component has a free and an anchored end; and one end of the power cable is connected to the free end of the elastically deformable component.
 24. A compound bow as defined in claim 19 wherein the timing mechanism for synchronizing the rotations of the string cams comprises: first and second timing wheels respectively rotatable with the first and second string cams; and a flexible, generally inextensible component which extends between and around and is fixed to the first timing wheel and the second timing wheel.
 25. A compound bow as defined in claim 24 wherein the flexible timing mechanism component has a figure 8 configuration.
 26. A compound bow as defined in claim 24 in which the compound bow has at least one feature for holding the flexible timing mechanism component out of the path followed by an arrow shot from the bow. 